It has been found when evaluating the performance of current-limiting fuses that the performance of identical specimens under identical testing conditions varies within a relatively wide range. Radiographs taken of such fuses after blowing thereof revealed the reasons for the difference in performance. To be more specific, whether the fulgurite is closer to the inner surface of the casing, or is closer to the longitudinal axis thereof, has a great influence on the performance of the fuse and the radiographs of blown fuses revealed, that significant changes as to position of the fusible elements, or as to position of the fulgurites resulting therefrom, had occurred. Another reason for observed differences in performance of identical specimens under identical testing conditions lies in the fact that different amounts of arc-quenching filler are associated with the same increments of the fusible elements or, to say it in another way, that the fuse metal is not sufficiently equally distributed in the pulverulent arc-quenching filler.
It is, therefore, the prime object of the present invention to provide current-limiting fuses that are not subject to the above limitations.